An outbreak of strangles associated with a novel genotype of Streptococcus equi subspecies equi in donkeys in China during 2018.

BACKGROUND: Strangles is a highly contagious respiratory disease of equids caused by the bacterium Streptococcus equi subspecies equi. OBJECTIVES: To identify the cause of an outbreak of strangles that occurred on donkey farms within the Shandong Province of China and determine the prevalence of the disease. STUDY DESIGN: Cross-sectional. METHODS: Samples were taken from clinically affected animals to measure the prevalence of strangles within the population of donkeys at six intensive farms in China and identify the SeM type of isolate recovered from affected animals. Diagnosis was confirmed by bacterial isolation, biochemical tests and PCR. Epidemiological data were analysed using Chi-square test and a Fisher's exact two-sided test. The SeM gene of S. equi isolates recovered from affected animals was determined and compared with the SeM database PubMLST-seM. RESULTS: In July and August 2018, an outbreak of strangles occurred on six donkey farms within the Shandong Province of China. The overall prevalence of disease within the different donkey herds was 13.4%. Younger animals were worst affected with 40.3% (83/206) of donkey foals aged under 1 year exhibiting clinical signs compared with 12.5% (191/1525) of donkeys aged one to 2 years and 3.8% (17/442) of donkeys over 2 years of age. Analysis of SeM sequencing data identified that the farms were affected by the same strain of S. equi, SD201807, which contains the novel 136 allele of SeM. MAIN LIMITATIONS: Healthy donkeys were not sampled in this study. CONCLUSIONS: The number of intensive donkey breeding farms in China has risen recently. The higher numbers of animals that are in closer proximity to one another raise the potential for the transmission of infectious diseases such as strangles. This is the first description of a strangles outbreak among donkey herds in China. The Summary is available in Chinese - see Supporting information.

Campylobacter and Salmonella are prevalent in broiler farms in Kyushu, Japan: results of a 2-year distribution and circulation dynamics audit.

AIM: To elucidate the distribution and circulation dynamics of Campylobacter and Salmonella in Japanese chicken broiler flocks. METHODS AND RESULTS: A 2-year investigation of the distribution of Campylobacter and Salmonella was conducted in 25 broiler flocks at nine farms in Japan from 2013 to 2014. Campylobacter and Salmonella tested positive in 11 (44·0%) and 24 (96·0%) broiler flocks respectively. One hundred and ninety-five Campylobacter and 184 Salmonella isolates were characterized into 12 Campylobacter (including two novel genotypes) and three Salmonella MLST genotypes. Only Salmonella isolation between caecal and environmental samples were significantly correlated. Further, one litter sample tested positive for Salmonella before new chicks were introduced. The Campylobacter strains rapidly lost culturability within 2-18 days; in contrast, the Salmonella strains survived from 64-211 days in artificially inoculated water samples. CONCLUSION: No persistent circulation-mediated Campylobacter contamination was observed. In contrast, circulation of Salmonella in broiler houses was seen, apparently due to the litter excreted from broiler flocks, as well as Salmonella-contaminated water and feed. SIGNIFICANCE AND IMPACT OF THE STUDY: This paper provides the distribution, genotypic data and circulation dynamics of Campylobacter and Salmonella as recently observed in Japanese chicken broiler farms.

Prospects for recombinant vaccines against Babesia bovis and related parasites.

Babesial parasites infect cattle in tropical and temperate regions of the world and cause significant morbidity and mortality. Discovery of protective antigens that could be used in a killed vaccine has been slow and to date there are few promising vaccine candidates for cattle Babesia. This review describes mechanisms of protective innate and adaptive immune responses to babesial parasites and different strategies to identify potentially protective protein antigens of B. bovis, B. bigemina, and B. divergens. Successful parasites often cause persistent infection, and this paper also discusses how B. bovis evades and regulates the immune response to promote survival of parasite and host. Development of successful non-living recombinant vaccines will depend on increased understanding of protective immune mechanisms and availability of parasite genomes.

A novel 20-kilodalton protein conserved in Babesia bovis and B. bigemina stimulates memory CD4(+) T lymphocyte responses in B. bovis-immune cattle.

Acquired immunity against the hemoprotozoan parasite Babesia bovis is believed to depend on activation of antigen-specific CD4(+) T lymphocytes and IFN-gamma production. A strategy was employed to identify potentially protective antigens from B. bovis based on memory CD4(+) T lymphocyte recognition of fractionated merozoite proteins. Fractions of merozoites separated by continuous flow electrophoresis (CFE) that contained proteins of approximately 20 kDa were shown previously to stimulate memory CD4(+) lymphocyte responses in B. bovis-immune cattle with different MHC class II haplotypes. Expression library screening with rabbit antiserum raised against an immunostimulatory 20-kDa CFE fraction identified a 20-kDa protein (Bbo20) that contains a B lymphocyte epitope conserved in geographically distant B. bovis strains. An homologous 20-kDa protein that has 86.4% identity with Bbo20 and contains the conserved B cell epitope was identified in B. bigemina (Bbg20). Southern blot analysis indicated that both Babesia proteins are encoded by a single gene. Antibody against recombinant Bbo20 protein identified the antigen in CFE fractions shown previously to stimulate memory T lymphocyte responses in immune cattle. To verify Bbo20 as an immunostimulatory T lymphocyte antigen, CD4(+) T cell lines were propagated from B. bovis-immune cattle with merozoite antigen and shown to proliferate significantly against recombinant Bbo20 protein. Furthermore, Bbo20-specific CD4(+) T cell clones proliferated in response to several B. bovis strains and produced IFN-gamma. BLAST analysis revealed significant similarity of the Bbo20 and Bbg20 amino acid sequences with the hsp20/alpha-crystallin family.

DNA from protozoan parasites Babesia bovis, Trypanosoma cruzi, and T. brucei is mitogenic for B lymphocytes and stimulates macrophage expression of interleukin-12, tumor necrosis factor alpha, and nitric oxide.

The activation of innate immune responses by genomic DNA from bacteria and several nonvertebrate organisms represents a novel mechanism of pathogen recognition. We recently demonstrated the CpG-dependent mitogenic activity of DNA from the protozoan parasite Babesia bovis for bovine B lymphocytes (W. C. Brown, D. M. Estes, S. E. Chantler, K. A. Kegerreis, and C. E. Suarez, Infect. Immun. 66:5423-5432, 1998). However, activation of macrophages by DNA from protozoan parasites has not been demonstrated. The present study was therefore conducted to determine whether DNA from the protozan parasites B. bovis, Trypanosoma cruzi, and T. brucei activates macrophages to secrete inflammatory mediators associated with protective immunity. DNA from Escherichia coli and all three parasites stimulated B-lymphocyte proliferation and increased macrophage production of interleukin-12 (IL-12), tumor necrosis factor alpha (TNF-alpha), and nitric oxide (NO). Regulation of IL-12 and NO production occurred at the level of transcription. The amounts of IL-12, TNF-alpha, and NO induced by E. coli and protozoal DNA were strongly correlated (r2 > 0.9) with the frequency of CG dinucleotides in the genome, and immunostimulation by DNA occurred in the order E. coli > or = T. cruzi > T. brucei > B. bovis. Induction of inflammatory mediators by E. coli, T. brucei, and B. bovis DNA was dependent on the presence of unmethylated CpG dinucleotides. However, at high concentrations, E. coli and T. cruzi DNA-mediated macrophage activation was not inhibited following methylation. The recognition of protozoal DNA by B lymphocytes and macrophages may provide an important innate defense mechanism to control parasite replication and promote persistent infection.

Avaliaçäo da técnica de western blot no diagnóstico da leucose enzoótica bovina / Evaluation of western blotting for the diagnosis of enzootic bovine leukemia

Um sistema de western blotting (WB) foi desenvolvido para detecçäo de anticorpos contra o vírus da leucose em soros bovinos. Foram utilizadas amostras de soros de 233 animais naturalmente infectados e soros de vacas experimentalmente infectadas. O teste de imunodifusäo em ágar (AGID) foi usado para comparaçäo dos resultados. Graus diferentes de reatividade foram observados em soros positivos ao AGID, quando testados em WB frente a um ou aos dois antígenos mais importantes (gp51 e p24). Outras proteínas (gp30, p15, p12 e p10) näo foram detectadas por nenhum soro positivo ao AGID, sendo que três bandas correspondentes à proteína p24 foram observadas ocasionalmente. Em soros obtidos por inoculaçäo experimental, anticorpos contra a proteína p24 foram detectados entre a segunda e a quarta semanas após a inoculaçäo e, em alguns animais, detectaram-se anticorpos anti-gp51 mais tardiamente. O estudo de soros de campo com AGID e WB mostrou concordância de 90,9 por cento sendo que apenas 1,7 por cento dos soros negativos pelo AGID foram positivos ao WB e 7,2 por cento dos resultados näo conclusivos por AGID foram definidos por WB (4,2 por cento como positivos e 3 por cento como negativos)

Diversity of genomic electropherotypes of naturally occurring equine herpesvirus 1 isolates in Argentina.

The genomes of 10 equine herpesvirus 1 (EHV-1) strains isolated in Argentina from 1979 to 1991, and a Japanese HH1 reference strain were compared by restriction endonuclease analysis. Two restriction enzymes, BamHI and BglII, were used and analysis of the electropherotypes did not show significant differences among isolates obtained from horses with different clinical signs. This suggests that the EHV-1 isolates studied, which circulated in Argentina for more than 10 years, belong to a single genotype.

The major histocompatibility complex of ruminants.

Studies of the major histocompatibility complex (MHC) of cattle over the past twenty years have revealed a reasonably detailed picture of the genetic organisation and function of the genes within this genetic system. Serological and biochemical analysis of lymphocyte cell surface antigens provided the first evidence for highly polymorphic MHC genes in cattle and other ruminant species. The MHC of cattle was thus named the bovine leucocyte antigen (BoLA) system. During the past 10 years, tools of molecular biology have been used to characterise the number of MHC genes, their sequence and fine structure in a number of ruminant species. Although individual MHC genes were found to have clear orthologues among ruminants and other mammalian species, the MHC of cattle, and probably that of sheep and goats, has a unique genetic organisation. Cattle have a class II gene cluster (class IIb region) which is physically distant from all the other MHC genes on the same chromosome. Moreover, genes involved in antigen processing, such as the proteosome subunit locus LMP2, are also found in the class IIb region, demonstrating that these genes need not be in close proximity to other MHC genes to function normally. The MHC class I and class II gene products of ruminants present processed peptides to T lymphocytes which mediate helper and cytotoxic functions. Identification of peptide binding motifs of cattle MHC class I molecules indicates that ruminant MHC molecules function in a similar manner to those of mice and humans. These functional studies provide a firm molecular basis for a number of well-documented associations with infectious diseases, although a detailed understanding of the immunogenetic mechanisms underlying these associations has yet to be elucidated.

Diversity of genomic electropherotypes of naturally occurring equine herpesvirus 1 isolates in Argentina

The genomes of 10 equine herpesvirus 1 (EHV-1) strains isolated in Argentina from 1979 to 1991, and a Japanese HH1 reference strain were compared by restriction endonuclease analysis. Two restriction enzymes, Bam HI and Bgl II, were used and analysis of the electropherotypes did not show significant differences among isolates obtained from horses with different clinical signs. This suggests that the EHV-1 isolates studied, which circulated in Argentina for more than 10 years, belong to a single genotype

Characterization of several pseudorabies viral strains by virus-neutralization test using monoclonal antibodies.

In the present study, five mouse monoclonal antibodies (MAbs) to the pseudorabies virus (PRV) Yamagata-81 strain were produced. The MAbs were used in cross-neutralization tests and cross-indirect enzyme-linked immunosorbent assay (ELISA) against three PRV viral strains isolated in Argentina and another four obtained from the United States, Japan, France, and Sweden. Four of five MAbs needed the presence of complement to produce or enhance neutralization activity. No differences were observed by ELISA. The MAbs showed different neutralizing activity against PRV strains, suggesting phenotypic heterogeneity among them.

The genotype of Aujeszky's disease viruses isolated in Argentina.

Genomes of four Argentine isolates of Aujeszky's disease virus (ADV) (Rio Cuarto/79, Mercedes, Chanar Ladeado-7 and Chanar Ladeado-15) from pigs were characterized and compared with four ADV strains obtained from U.S.A. (Indiana-S), Sweden (Sweden 66), France (Alfort) and Japan (Yamagata-S81) by restriction endonuclease (RE) analysis. Although three Argentine isolates were classified into type I of BamHI cleavage pattern, one isolate, Mercedes, belonged to type II, according to the classification by Herrmann et al. [6]. Since this type II virus was first isolated in 1981, no outbreak of ADV infection by this type has so far been reported in Argentina. This may imply that the immediate measures by total slaughter of pigs in the farm led successful eradication of the type II ADV infection in Argentina. This report is the first epidemiological study using RE analysis on ADV strains in this country.

Isolation, sequence and expression of a cDNA encoding the alpha-chain of the feline CD8.

We have cloned, sequenced and expressed a cDNA encoding the alpha-chain of feline CD8. This clone, named FT8-10, has an open reading frame with 720 nucleotides in length encoding a protein with 239 amino acid residues. Sequence analysis has revealed that the feline CD8 alpha-chain (CD8 alpha) shares significant homology with human (T8/Leu-2), bovine (BoCD8), rat (MRC OX8) and mouse (Lyt-2) CD8 alpha subunits. Cysteine residues as well as the tyrosine kinase p56lck binding site are well conserved. Besides, no putative N-linked glycosylation site was found. Interestingly, immunofluorescence analysis of COS-7 cells transfected with feline CD8 alpha expression plasmid driven by SR alpha promoter showed that the expressed feline CD8 alpha cross-reacted with an anti-human CD8 alpha monoclonal antibody OKT8, but did not react with an anti-feline monoclonal antibody, FT-2, which is thought to recognize the feline analogue of the human T8/Leu-2 and murine Lyt-2 molecules expressed on cytotoxic/suppressor T cells.

Feline CD4 molecules expressed on feline non-lymphoid cell lines are not enough for productive infection of highly lymphotropic feline immunodeficiency virus isolates.

To investigate whether the feline CD 4 (fCD4) molecules are involved in infections of highly lymphotropic feline immunodeficiency virus (FIV) isolates, we expressed fCD4 stably on Crandell feline kidney cells and Felis catus whole foetus 4 cells by transfection of a cDNA encoding the fCD4 glycoprotein, and then infected them with TM 1 and TM 2 strains of FIV, which are unable to infect these cells productively. In spite of fCD 4 being expressed on these cells, no virus production was observed. This result indicates that fCD 4 expression alone cannot induce a productive infection of the FIV TM 1 and TM 2 strains.

Monoclonal antibodies to feline lymphocyte membranes recognize the leukocyte-common antigen (CD45R).

By immunization of BALB/c mice with a feline T lymphoblastoid cell line, MYA-1 cells, two types of lymphocyte-specific monoclonal antibodies (mAbs) were obtained. The 220/205/190 kd protein defined by 2F11 mAb is highly expressed on the surface of MYA-1 cells and another feline T lymphoma cell line, FL74 cells. The protein is also expressed on normal feline thymocytes, splenocytes and feline peripheral blood mononuclear cells (PBMCs). Another mAb, 17B10, caused similar results as those of 2F11 except for its low reactivity with FL74 cells. The second type of mAb, 15B3, defined the 220 kd protein. The reactivities of this mAb with MYA-1 cells, FL74 cells, PBMCs and feline splenocytes were lower than the former two mAbs, and did not react to feline thymocytes. On the other hand, 17B10 and 15B3 defined partial populations of MYA-1 and FL74 cells recognized by 2F11. The cells defined by the 2F11 and 17B10 are all leukocytes in spleen and lymph node. In contrast, 15B3 defined most of the cells in B cell area and partially in T cell area. These results suggested that 2F11 and 17B10 recognized the specific antigen of 220/205/190 kd of the leukocyte-common antigen (L-CA) family, CD45R, with different epitopes, and that 15B3 defined the distinct antigen of 220 kd on CD45R.

Identification of a feline immunodeficiency virus gene which is essential for cell-free virus infectivity.

Feline immunodeficiency virus (FIV) contains at least three small open reading frames (ORFs) in the genome, in addition to the three structural genes. Two of these ORFs (putative vif and ORF-A) have unknown functions. Northern (RNA) blot analysis of mRNAs from an FIV-infected cell line showed that the putative-vif-specific mRNA was expressed as a 5.2-kb species. To examine the function of the putative vif gene, we constructed mutants carrying a deletion in either the vif-like gene or the rev gene from an infectious molecular clone of FIV. Although the vif mutant produced virion-associated reverse transcriptase at a normal level upon transfection, cell-free virus prepared from the transfected cells could not infect feline CD4+ cells. The infectivity of the vif mutant, however, was demonstrated in a coculture of the transfected cells and feline CD4+ cells. We conclude that FIV contains the vif gene, which is structurally and functionally similar to that of the primate lentiviruses.

Sequences within the feline immunodeficiency virus long terminal repeat that regulate gene expression and respond to activation by feline herpesvirus type 1.

We constructed a series of deletion mutants of feline immunodeficiency virus (FIV) long terminal repeat (LTR) to identify the regions that regulate gene expression and are responsive to trans-activation of FIV LTR by feline herpes-virus type 1 (FHV-1). We demonstrated that sequences between -124 and -79, and between -21 and -32 (relative to the cap site) are essential for gene expression of FIV in Felis catus whole fetus 4 (fcwf-4) cells. Further, we demonstrated that the sequence between -63 and -23 responds to trans-activation of FIV LTR by FHV-1 in fcwf-4 cells.

Identification and nucleotide sequence of a gene in feline herpesvirus type 1 homologous to the herpes simplex virus gene encoding the glycoprotein B.

The nucleotide sequence of the glycoprotein B (gB) homologous gene of feline herpesvirus type 1 (FHV-1) was determined. The gene was found to be located within a 9.6 kbp SalI fragment by Southern-blot hybridization with a probe derived from the herpes simplex virus type 1 (HSV-1) gB DNA sequence. Furthermore, the predominant portion of the coding sequences was mapped to a 1.9 kbp Hin cII-EcoRI and its flanking 2.7 kbp Eco RI-Eco RI subfragments in the 9.6 kbp SalI fragment. The entire nucleotide sequence revealed that the FHV-1 gB homologous gene is capable of encoding a polypeptide of 948 amino acids. The predicted precursor polypeptide derived from this open reading frame could have a calculated M(r) of 106 kDa in unglycosylated form and contains ten potential N-linked glycosylation sites and a probable internal proteolytic cleavage site. By Northern-blot analysis using portions of the open reading frame as a probe, 3.9 and 3.3 kb RNA transcripts were identified in FHV-1 infected cells. The alignment of the amino acid sequence of the FHV-1 gB homologue with those of 14 other herpesviruses revealed that 10 cysteine residues were completely conserved. Meanwhile, when evolutionary trees were generated among these herpesvirus gB counterparts, the FHV-1 gB homologous nucleotide sequence seems to be closely related to equine herpesvirus type 4 and its amino acid sequence to pseudorabies virus.

Replicative difference in early-passage feline brain cells among feline immunodeficiency virus isolates.

The susceptibility of early-passage feline brain cells and Crandell feline kidney (CRFK) cells to infection with three isolates of feline immunodeficiency virus (FIV) was investigated. The Petaluma strain of FIV could well infect both the feline brain cells and CRFK cells. The KYO-1 strain could well infect the feline brain cells but the replication in CRFK cells was demonstrated only by coculturing fresh feline T-lymphoblastoid cells with the infected cells. On the other hand, the TM1 strain could infect the feline brain cells but not CRFK cells. Moreover, the replicative ability of the TM1 strain in the feline brain cells was much less than the KYO-1 and Petaluma strains. These results indicate that biological differences can be detected among the FIV isolates.